1. Field of Invention
This invention relates to methods for obtaining closely matched die sets in molding and forming press setups for the production molding of diaphragms and like structures with thin coated fabrics; more particularly to methods for creating a closely matched die set in a given setup on a mold machine for molding diaphragms from rubber coated fabric.
2. Background Art
Thin, coated fabrics are used for molding or forming a variety of specialty products including very small flexible diaphragms which must exhibit very consistent operating characteristics. The problem in using a traditional mold for producing these products is in the machining and set up of the male and female halves of the mold to a close enough tolerance. When they are brought together with a very thin layer of material between them, there are likely to be voids for which a significant amount of flow of the coating is required to fill. Excessive voids require excessive temperature and pressure to achieve the necessary flow, and this increases the likelyhood of inconsistant performance of the product from one setup to the next, and from one cycle to the next.
The following prior art provides useful context for better understanding the invention:
U.S. Pat. 4,889,668 discloses a fixed-volume, trapped rubber molding method encompassing a complex temperature and sensor apparatus used in conjunction with casting elastomeric material cured around the die to form a die support structure.
U.S. Pat. 5,700,496 discusses a self adjusting backplate for supporting one or both sides of the mold plates of a blow-molding machine with a cushioning material on the outer plate surface. The specially designed cushioning material allegedly absorbs the pressure and allows the molding to proceed without shims, providing equal pressure along the mold plates.
U.S. Pat. 5,093,067 shows a method for injection molding of fabric reinforced elastomer diaphragms, where a fabric is placed between a mold plates. Elastomeric material is injected into the mold through ports and allowed to cure, producing thin diaphragms without migration or distortion of the fabric.
Skilled practitioners will appreciate the short comings of the prior art as contrasted to the benefits of the instant invention, including the desirability for achieving a closing confirming die pair setup, and reducing the problem of voids and the need for flowing of coating material when using coated fabrics for forming or molding formed articles such as diaphragms.